Improvement in boring-tool



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`ALEXANDER ALL-AN,-

o'rNEw Yon-K, N. Yy

Lenen Pate-n1: No. 95,627, dated ouate-'12, 18,69.

IMPROVEMENT IN BORING-TQOL.

The Schedule referred to in these Letters Patent and making part of thesame.

To all whom 'it 'ma/y concern:

Beit known that I, ALEXANDER ALLAN, of the city, county, andI State ofNew York, `have invented a new and useful Tool for Boring Square Holes;and I do hereby declare the following to be a fuiland correctdescription of the same, reference being had to the accompanyingdrawings, in which- Figure 1 is a perspective view-of the tool.

Figure 2 is a vertical section of the same.

Figures 3, 4, 5, 6, and 7, are diagrams illustrating the theory of theoperation of the tool. p

' Figure 8 is a top view'of the toolguide and its ring. 4The saineletter marks the same part of .the .tool Wherever it occurs.

The nature of the invention consists in the peculiar manner ofconstructing, attaching, and operating a boring-tool, by which it ismade to bore square, or nearly square holes, in wood, sheet-metal, orother materials, as hereinafter more particularly set forth. ,y

To enable others to make and use my boring-tool, I will proceed todescribe its construction dand operation.

The tool is supported on a firm base, A, to whichis attached'theclamping-box B, by means of the straps Inside of lbox B is theI cla-mpD, which holds the work, and which is adjusted by the screws s s.

From the top of the box B rises the hollow standard E, which is screwedinto a recess in B, as shown in g. 2.

Below the standard E is inserted a ring, F,which turns in the recess,which receives it and is held in any desired position by the set-screws'.

In the middle of this ring is the square guide G, iigs. 2 and 8.

This guide receives the triangular cutting-tool H, which turns in itwhile performing its work.

The tool -H is inserted iu a tol-stock, I, threaded at its -upper end,and working loosely in afemale screw in'the'upper end of the standard E.

A small amount of play of the tool-stock is essential to the properoperation of the tool, but a slight excess of play is not detrimental. vA handle, K, attached to the top of the tool-stock I, serves to operatethe tool.

The operation is as follows:

The article to be bored is inserted in the clamp-box' B, and held by theclamp D', adjusted' by the screws The g'uide G is adjusted to its properrelative position to the work by turning the ring E and holding it bythe set-screw s. Q

By means of the handle K, the tool H 1s caused to descend till it passesinto the hole in the basel-L, through the article subjected to itsaction.

The hole produced will be square, and correspond in I -the centre of thetriangle forming its cross-section.

The rationale-of the operation will be explained'by reference to thediagrams,1figs. 3,. 4, 5, 6, and 7 Iii these diagramma b c is anequilateral triangle, representing .the cross-section ofthe tool H, dniarking the point of the tool,

I In g. 7, the triangle is shown iu the middle of'a Y square, e f y h,representing the square opening in the guide Gr.v

. The line i f, in this gureshows the amount of playvnecessary to theproper operation of the tool in a guide of' this size. l L In gs. 3, 4,'5, and 6, the triangles a b c represent the four positions of the tool,in relation to the square opening in the guide G, assumed during onerevolution.

The action appears to be as follows:

Then the point-l of the tool encounters the surface of the wood or metalto be bored, it meets with suilicient resistance to thrust it to oneside until one of the angles. of the tool is driven into one of theangles of the guide. It then occupies, let us suppose, the positionrepresented in fig. 3. In that position, the angle c becomes a centre ofrotation, and

the angle b describesthe arc bj. This brings the' Vtool into theposition represented in fig. 4. Here the point b becomes a centre, andthe point c describes the arc a f. A This brings the tool into theposition represented in g. 5, wherethe point c becomes a centre,y

and the point 'c describes the arc c f. v

The tool is now inthe position shown in g. 6, point c becoming acentre,and the point b describing arc b e..

This last movement brings the tool into its initial position in relationto the guide, with the exception that the side b c of the tool isin.contact with the left side of the guide-opening, instead of the sidea c, as in iig. 3.

By changing the form of the guide, angular holes, of other forms thansquare, may be bored on the same principle of operation.

Practice will enable a skilful workman to use lthe tool without a guide,in an ordinary brace, giving the requisite eccentricity or play to thetool by his judgment alone.

, The guide suppliesthc place of this skill to inex` perienced hands. v

Having thus fully described my invention, `and the principle of itsoperation,

. What I claim, and desire to secure by Letters Patent, is-

1. The triangular toolH, with the pyramidal point working' in the guideG, with the necessary eecen; tricity to reach the angles of the guide,as described.

2. The combination' and arrangement of the clamp# ng-box BY, hollowstandard E, tool-stock I, and tool H, in the manner and for the purposespecified.

3. A tool, constructed as described, for boring rectangular and otherangular holes, bv having au eccentlemovement or play `*communicated toit by the operator, in the manner set forth.

The above specification of my said invention, signed` and witnessed atWashington, this 24th day of May, A. D. 1869.-

ALEX. ALLAN.

Witnesses:

A. C. BRADLEY, OHAs. F. STANSBURY.

